The present invention relates to a polishing slurry and a polishing method using the same. More specifically, the present invention provides a novel polishing slurry used in chemically and mechanically polishing an interlayer insulating film (SiO2) and a metal film formed on a silicon wafer, and a polishing method using the same.
As semiconductor devices are highly integrated, wiring techniques advance more and more toward fineness and multilayer. Advance toward fineness and multilayer in wiring increases and steepens a difference in a level between layers, so that a processing accuracy and a reliability of the wirings formed thereon tend to be lowered.
Chemical and mechanical polishing (hereinafter abbreviated as CMP) is paid attentions for solving the problems described above. A CMP method is a means for polishing an interlayer insulating film such as a silicon dioxide film and a metal film of aluminum, tungsten or the like which forms a wiring layer to thereby planarize them in a production process of semiconductor devices. A higher polishing rate, less contamination of a material to be polished, smaller scratches and a higher selectivity are required to polishing slurry used in CMP.
The preceding performances of the polishing slurry depend largely on abrasive grain components such as silica and cerium oxide which are principal raw materials. For example, a polishing slurry using fumed silica for abrasive grains which has so far been often used does not necessarily have a satisfactory polishing rate and has been desired to be further improved in a polishing rate. Particularly in a semiconductor production process, the polishing rate is related to a productivity of devices, and therefore it has been strongly desired to elevate the polishing rate.
An object of the present invention is to provide a polishing slurry having a high polishing rate which is used for CMP.
Another object of the present invention is to provide a polishing slurry having a high productivity, which makes it possible to polish a device.
The preceding objects of the present invention can be achieved by a polishing slurry comprising water, fumed silica and spherical silica having an average primary particle size of 40 to 600 nm excluding the fumed silica.